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MECHANICAL DRAWING 



LETTERING, MATERIALS 
AND METHODS 



BY FRANK R. KEPLER 

Cass Technical High School Drafting Department 




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Published under Authority of 

THE BOARD OF EDUCATION 

Detroit, Michigan 






Copyright 1916 

by 

FRANK R. KEPLER 



Printed in 

Cass Technical High School 

Detroit, Michigan 



.K4 



MECHANICAL DRAWING 

F, R. Kepler 
INTRODUCTION 



Broadly speaking, Mechanical Drawing may be understood 
to mean drawing done with, the aid of instruments. More strictly, 
it may mean the drawing of machines or things mechanical as 
distinguished from architectural drawing, for instance. Mechan- 
ical drawings of machines are often called working drawings, of 
buildings they are called plans. Such drawings convey the ideas 
Oi the originator or engineer to the mechanic or the workman. 
Mechanical drawing, then, may be said to be the language of the 
engineer, the architect:, the mechanic. The musician conveys his 
ideas by means of music, the artist by means of his picture. 

An inventor or designer often spends weeks and months on 
some contrivance or plan. He probably makes many calculations. 
It would be almost impossible for him to remember all the details 
and scores of dimensions, much less to tell them to some one else. 
The dravvmg then furnishes him with a means of recording his 
ideas and calculations and showing details of construction. 

The requirements of a good draftsman are neatness, accuracy 
and rapidity. By neatness is meant that not only must the drafts- 
man keep his drawing clean, but he must arrange it neatly. The 
student must cultivate the habit of making clean, sharp lines and 
neat, well-arranged drawings. Unless a drawing is made in a 
workmanlike manner, the work on the contrivance is not apt to 
be performed in a thorough manner. 

Accuracy, too, is most important. It is evident that unless a 
drawing is made accurate in detail and dimensioned accurately, 
work made from it will not be as planned. It will often be found 
impossible to make the thing at all or costly mistakes will result. 
Much valuable time, labor, and material will be wasted because of 
a careless draftsman and checker. 

A draftsman should not only be neat and absolutely accurate, 
but he must be able to make a drawing in a reasonable length of 
time. No matter how good a draftsman may be, an employer 
can hardly afford to keep him unless he has a certain degree of 
rapidity. However, accuracy and neatness should not be sacri- 
ficed for rapidity. Rapidity greatly depends on how one takes hold 
of a piece of work, his order of procedure. A regular order should 
be acquired. 



MECHANICAL DRAWING 



The beginner taking up the study of mechanical drawing for 
the first time must of necessity learn the names and uses of the 
instruments and tools employed. We may say that the tools of 
the draftsman do not necessarily mean the special drawing instru- 
ments alone, but include a working knowledge of conventional 
fines and standards and a ready skill in making well formed letters. 
Proficiency in lettering is most essential to a draftsman. There- 
fore, a careful study will be made of one form of lettering and 
considerable practice given not only in lettering but in the use 
of mechanical drawing instruments and materials. 



JUL -5 1916 

els' 

©CI.A4;53607 



LETTERING 



LETTERING 

F. R. Kepler 

The subject of lettering is of great importance to the mechan- 
ical draftsman. Many well executed drawings have been disfig- 
ured by poor lettering. 

Every draftsman must be able to letter a drawing neatly and 
rapidly. Any system of letters suitable for working drawings must 
not only be neat in appearance but well proportioned. Artistic 
finish is secondary to plainness and speed. A simple form is neces- 
sary; first, that dimensions and notes may be so easily read by the 
workman that he may have no excuse for committing a blunder; 
second, that the letters may be easily and rapidly made in order to 
keep the cost of the drawing low. While artistic lettering requires 
a particular aptitude and a natural fitness for the work, a simple 
style is within the reach of any draftsman, and ignorance upon this 
important subject is inexcusable. 

Since it is the almost universal practice to use only capital 
letters upon working drawings and owing to the limited time at 
the disposal of the student, attention at first should be given to the 
making of capitals only. It is evident that in the time allowed 
much better results can be obtained through practice upon but 
one form of letter 

A common fault with a beginner is to leave too httle space 
between the words and too great space between the letters com- 
posing the words. The beginner must copy from good models 
all the different kinds of characters and thus acquire a perfect 
knowledge of the proper proportions of every letter. Proficiency 
can be acquired only by practice. 

As tracings are made of most drawings and blue prints are 
made from these, it is necessary that the corners of the letters be 
made sharp and clean; the curves round and full so that they will 
not fill in when inked. The bold lines should be made freely. The 
use of waterproof ink necessitates wiping off the pen frequently 
and working the points between the fingers to loosen the dry ink. 

Various systems of simple letters are in use. The main re- 
quirement of any system is that good execution and a fair degree 
of rapidity be easily acquired. In the system employed in this 
course, only two elements are used; namely, the straight line and 
the elhpse. The letters are five (5) spaces high, being inchned 



MECHANICAL DRAWING 



two (2) spaces to the right, making the inclination about 22i/, 
deg. from the perpendicular. 

As this system of lettering is designed for use in connection 
with working drawings and blue printing, the formation of the 
letters is determined largely by that fact and that it is often neces- 
sary to make them in ink with a pen. Experience has proven 
that most letters are most successfully made by employing two or 
more strokes downward. The letters must all appear broad. Bear 
in mind that the letters must be made with care, drawn, if you 
please, rather than printed. Remember that the spirit of a me- 
chanical drawing is precision, accuracy. The lettering must bear 
out this feeling and at the same time be well proportioned in 
design. 



LETTERS 

To aid the beginner, a detailed description will be made of 
each letter. Upon examination we find that the letters are divided 
into groups, those made up of straight lines only, including those 
formed of the inclined stroke and the horizontal stroke; those 
made of the ellipse or a modification of it; and those made by a 
combination of the straight line and the elhpse. 




The letters I, L, F, E, H, and T compose the first group. The 
capital I consists of a simple inclined stroke. It is never dotted. 
If it stands alone or would otherwise be confusing, horizonfal 
strokes are often made across the top and bottom. L should be 
made by making the slanting stroke down and then the horizontal 
stroke to the right. The length of this stroke is four-fifths (4/5) 
of the height. F is made with the inclined stroke first, then the 
horizontal stroke at the top is made four-fifths (4/5) of the height 
and the third, horizontal stroke, just a little below the center, is 
one-half as long as the height of the letter. The E is begun just 
as the letter L is made and then the upper and middle horizontal 
strokes are made just as in the letter F. However, the short stroke 
is made a little above the center in order to give a sense of stability 
to the letter. Do not make the last stroke too long. 

H consists of two inclined parallel strokes a little more than 
four spaces apart making the width of the letter a trifle better than 
four-fifths (4/5) of its height, a horizontal stroke just a little 



LETTERS 

above the center comi3letes the letter. Care should be taken to 
make this stroke straight across. The inclined stroke of the T is 
made first, and then the horizontal stroke at the top from left to 
right, being careful to make it perfectly horizontal. This stroke 
is made four and a half (41/2) spaces long, two and a half (21/0) 
spaces being at the left. 

N, M, Y, X, A, K, V, W, and Z compose the group made up of 
inclined and' diagonal strokes. The N, like the H, must be made 
four (4) spaces wide. The inclined stroke on the left is made 
first, then the diagonal stroke from the top downward, being sure 
that it is inclined two spaces at least. The last stroke on .he right 
is made downward and parallel to the first. To insure making a 
good M, it is necessary to make the two inclined strokes at the 




left and right first. They are made parallel and five (5) spaces 
apart, the letter being of the same width as the height. The two 
diagonal strokes are made to meet at the center by drawing the 
lines as if they continued across the letter rrom corner to corner. 

The Y is more readily made by making first the inclined stroke 
at the top and left at the same slant to the left as the stem of 
the letter is to the right. Second, make the stroke at the right 
downward, starting at a point four and a half (41/2) spaces to the 
left and meeting the first just half way down the height of the 
letter. Third, make the stem of the Y downward inclined like 
the I. Great care must be taken not to make the letter too narrow 
nor the last two strokes too nearly in the same straight line. To 
made the X properly, make the stroke from the right downward, 
bringing it six (6) spaces to the left. The second stroke begins 
four and a half (41/2) spaces to the left and is inclined about 60 
degrees. When completed, lines drawn at either side would be 
inclined two (2) spaces, the whole letter having the proper 
inclination. 

In making an A, which is as broad as it is high, make the 
stroke on the left first downward at an angle of 45 degrees, nearly. 
Make the stroke on the right downward so that it slants outward 
a half of a space. In a small-sized letter, this stroke may be made 
vertical. The horizontal stroke must be made perfectly horizontal 
well below the center, a space and a half above the bottom. The 
K is four spaces wide. First, the inclined stroke at the left is 
made just as an I, the second begins four (4) spaces to the right 
of the first at the top and joins the first two (2) spaces above the 
bottom of the letter; the third stroke is made downward from the 
second three (3) spaces above the bottom to a point four (4) spaces 
to the right of the lower end of the first. 



6 MECHANICAL DRAWING 



V and W are very similar. The top of the first stroke at the 
left inclines a half space to the lelt. The second stroke begins 
four and a half (41/2) spaces to the right and is made downward 
to meet the first. W is made very similarly except that the parts 
are slightly narrower, being four spaces wide. In a small-sized 
letter, the first stroke may well be made vertical. In the Z, make 
the upper horizontal stroke first, then the diagonal stroke down- 
ward to the left six (6) spaces to the left of the upper end. Make 
the first stroke four and a half (4%) spaces long, the last five (5) 
spaces. 

O, Q, C, and G form a most important group. All are five (5) 
spaces wide, as broad as they are high. All are elliptical, the axes 
being at 45 degrees. Beginning at the top, form the left hand side 




of the ellipse, being careful to make the curve full and smooth. 
In hke manner, beginning at the top, form the right hand half. 
The Q is formed in exactly the same manner with the addition of 
the inclined stroke at the bottom. A letter C can best be formed 
by starting a short stroke downward from the top towards the 
right. Then with one stroke form the left half of the letter, con- 
tinuing on up into the lower right hand portion of the letter, 
making it end rather straight, one and a half spaces from the 
bottom. The G is made in just the same manner as the C, with 
the horizontal stroke a space and a half long. This last stroke 
must not extend outside the letter. 

The letter D is composed of a combination of straight lines 
and a portion of the ellipse. The inclined stroke is first made, 
then beginning at the top bring the line out horizontally two and 
a half spaces, form the right half of the ellipse and finish by con- 
tinuing horizontally to the lower end of the inclined stroke. The 
letter should be made fully four and a half (4%) spaces wide. 

U and J are made very similarly. Make the two sides of the 
U parallel and four and a half (4%) spaces apart first. Bring 
these down a trifie more than half the height. Form the lower 




portion, which is the lower half of an elhpse, beginning at the left. 
Be careful to make the lines join nicely. In the J draw the in- 
chned stroke continuing into about half of the curve. Finish the 
letter by beginning at the left, joining the curve nicely. 

P, R, and B may be grouped in on^ class. These are made up 
of straight lines and smaller elhpses. With P, make the inchned 
stroke first, begin at the top, start out horizontally for about two 
(2) spaces form the right half of an ellipse and bring the lower 



LETTERS 



line straight and horizontally to the inclined stroke three (3) 
spaces wide. R is made just as the letter P is made. The addi- 
tional stroke is made straight and as if it started a space to the 
right of the upper le^t hand corner and continued to a point making 
the letter five (5) spaces wide at the bottom. The first strokes 
of B are made as in P and R, although not quite so wide and join 
the inclined stroke a little above the center. The lower portion 
is made broader and higher. This form gives a sense of stability 
to the letter. 

The letter S, as indicated, is composed of the portions of two 
small ellipses with the axes extending horizontally. It should be 
formed by making the stroke from the top towards the right as 
in C and G. Beginning at the top, again draw the left half of 
the upper stroke. Finally add a downward stroke. The first and 
last strokes are oiten all that are needed to give the appearance 
of the proper inclination. Care must be taken to make the stroke 
at the center of the letter horizontal. The lower portion of the 
letter is often made higher than the upper, with very satisfactory 
results. This letter requires much practice. 



FIGURES 

Figures are perhaps the most important division of lettering. 
It is absolutely necessary that all figures shall be made plain. No 
doubt should be left as to just what the figure is. Especial atten- 
tion is therefore required for this branch of the subject. 

The 8 is quite similar in formation to the letter S. It is com- 
;xsed of two ellipses, one above the other, the axes being hori- 
zontal. By making the upper ellipse slightly narrower and less in 
height than the lower, a more pleasing figure is secured. There 
are four strokes, one to the right at the top, one to the left, one 
at the bottom and the last to the right at the bottom completing 
the figure. Join the portions carefully. 




3 is very easily formed, bearing in mind that the upper and 
lower portions aie parts o_ ellipses. It is best formed by begin- 
ning at the to^:;. bringing the curve well over to the right and 
ithout removing the pencil, form the lower curve. 

For the 2, start at the top, forming the loop smoothly and a 
little less in height than half the height of the figure. Continue 



MECHANICAL DRAWING 



into the reverse curve, bringing it pretty square to the bottom, 
and add the horizontal stroke four spaces long. This is a pleasing 
figure only when w^ell formed. Do not make the lower part too 
low and sharp. 

The 9 should be made four (4) spaces wide. The upper por- 
tion is a small ellipse fully three and one-half spaces high. The 
left half is made as lor an O, the right half formed, and, beginning 
well toward the top, complete the figure by forming the right and 
lower half of a large ellipse. Care must be taken to make the 
upper portion of sufficient height. Do not make it straight on the 
right. 

A 6 is formed first as if for the letter C and then, beginning 
at a point three-fifths (3/5) of the way down on the left, complete 
the small ellipse forming the lower portion of the figure. The 
lower portion is two-thirds (2/3) the entire height. 

In a 5, first make the inclined stroke, then form the body of 
the figure by making a portion of a full ellipse at least two-thirds 
(2/3) the height of the letter. Finally add the horizontal stroke 
at the top, three and a half spaces long. In making the figure, 
care must be taken to bring the elliptical part to its proper height 
above the lower end of the inclined stroke. 

Make the diagonal stroke of the 4 at 45 degrees, the horizontal 
stroke five and a half (5%) spaces long, and third the inclined 
stroke. Be sure to make the horizontal stroke of the figure a 
space and a half (11/2) above the base. This figure is commonly 
made too narrow. 

In the figure 7, the horizontal stroke is made four and a half 
(41/2) spaces long, and the diagonal stroke at 45 degrees is brought 
to a point at the bottom a space to the left of the starting point 
of the letter. 



EXERCISES 

The exercises and plates which follow are for drill and practice. 
Observe and study the formation of each character. Too great care 
cannot be taken in making each just right. Follow the directions to 
the letter. 




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12 



MECHANICAL DRAWING 




ARCHITECTURAL LETTERING 13 



ARCHITECTURAL LETTERING 

I. G. Koehler 

As architectural drawing is more decorative and artistic than 
mechanical, so architectural lettering must also lean toward the 
decorative and artistic, to be in harmony with the drawing. 

Both slant and vertical lettering are used; each having its 
advantage and disadvantage. The slant type is adapted to speed 
and medium class of work, the vertical to a more decorated and 
higher class of work. As will be noticed on the copy, the letter 
is composed of the straight line and the circle, making it a very 
simple and effective style of lettering. Students will be held to 
this one style of letter for the first term only, when they will 
begin to pick up letters of their own and which will finally lead to 
the student having an alphabet showing individuality. In no case, 
however, should a single letter be so far away from the accepted 
form that it would not be recognized without the companion letters 
at its side. 

Architectural lettering is made up of letters showing extremes, 
for instance the middle bar of the B, F, H, F, or S is placed very 
high or the lower bar of an R, P, 4, etc., placed very low. This 
style of lettering can be accomplished by a basic knowledge of 
mechanical lettering, copying good letters, and a great deal of 
practice. 

The lower case is used chiefiy for notes and should correspond 
in slant to that of the titles and sub-titles. The secret of good 
lower case lettering is in making extremely full curves and straight 
lines of the same slant. Finally, regarding all printing, the student 
should have a thorough knowledge of good spacing. 



14 



MECHANICAL DRAWING 



DRAWING INSTRUMENTS AND MATERIAL 

F. R. Kepler 

Drawing Board: — The drawing board should be made of some 
soft wood, such as pine, to allow the thumb tacks to be pressed in 
readily. The board must be so constructed as to prevent warping. 
The ends must be perfectly straight so as to give a good bearing 
for the head of the T-square. 



II2 o 





TEE SQUARE 



o 



Figure 1 

To fasten the paper to the board: — Adjust the paper in its 
proper position, put a thumb tack in one of the upper corners. Be 
sure to press it clear down to the head. Stretch the paper diag- 
onally to the lower corner and insert a second thumb-tack. Then 
stretch the paper from the center toward the two remaining cor- 
ners and fasten with thumb-tacks. In this way the paper may be 
made to he perfectly smooth on the board. Fig. 1. 

The Pencil: — Pencils are graded according to the degree of 
hardness. H denotes a soft pencil, a 3-H or 4-H being medium 
hard, while a 6-H is very hard. There are several grades from H 
to 8-H. For general use the pencil should be sharpened to a long 



DRAWING INSTRUMENTS 



15 



cone point. About a quarter of an inch of the lead should be 
exposed and this ground down to a fine point on a piece of sand 
paper. Accurate work depends largely on the sharpness of the 
pencil point. Fig. 2. 



Figure 2 

Penciling: — The pencil must be held hghtly between the fin- 
gers, about three inches from the end, to insure a light line. The 
line should be distinct, but great care is necessary in order to 
avoid bearing on too hard and thus creasing the paper. It is im- 
possible to erase such lines satisfactorily; the creases are most 
sure to remain to disfigure the drawing and make it difficult to 
ink. The penciled drawing should be made with great care. Ac- 
curacy must be practiced not only in order to attain accuracy but 
it is the custom at present to trace the penciled drawing on tracing 
paper or cloth prepared for the purpose. This tracing is often 
done by another person other than the one who has made the 
drawing. Therelore, it is evident that every line must be in its 
proper form, size, position and relation to every other Une, so that 
the tracer may have the drawing accurate. Make it a practice to 
make all the corrections in pencil before inking or tracing, other- 
wise costly blunders are sure to result. 







■ 


[I 


^:, 


II® ® 


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Figure 3 

T-square: — The T-square is composed of the head and the 
blade, generally fitted at right angles to each other. The head is 
the short, heavier piece, while the blade is the long, thin piece 
having a perfectly straight edge. It is customary to place the 
head against the left-hand edge of the board so that the blade 
extends across the board. Horizontal fines are drawn, using the 



16 



MECHANICAL DRAWING 



upper edge of the T-square as a guide. Fig. 3. The upper edge 
of the T-square is also used for placing the triangles against to 
draw vertical lines and lines at an angle. 

Triangles: — Pig. 1. Two triangles are ordinarily used. One 
has a right angle, or 90 degree angle, and two 45 degree angles. 
Two of its sides are equal. The other triangle has a 90 degree, a 
30 degree, and a 60 degree angle. None of its sides are equal. By 
using the 90 degree angle of either triangle against the T-square, 
vertical lines or lines perpendicular to the edge of the T-square, 
may be drawn. Pig. 3. By placing the triangles so that one of the 
other angles comes against the upper edge of the square, lines at 
45, 30, and 60 degrees may be drawn. By properly adjusting the 
two triangles, lines may be drawn parallel with any hne, 
even though it is not at 45, 30, or 60 degrees. Pig. 4. 




Figure 4 

An angle is formed by the meeting of two lines. Angles are 
measured by degrees. 11 we consider that the line oa, Pig. 7, has 
been revolved about the point o as a center until it has made one 
complete revolution, we say that it has revolved through 360 de- 
grees, a degree being one-three hundred sixtieth, 1/360, of a com- 
plete revolution. Degrees are indicated by the character, ^ . 
Again, if the line oa is revolved half way around, a is at b, and the 
line ob forms a straight line with oa. The line oa, then, has re- 
volved through 180/360 of a complete revolution, or 180^. An 
angle of 180 degrees is formed. If the line oa be revolved from its 
original position through one-fourth ( i/4 ) of a complete revolution 
to the position oc, it has been revolved 90/360 of a revolution, or 
90°. Thus an angle of 90 degrees is formed. This is called a 
right angle. Also if the line be revolved through one-eighth of a 
complete revolution to the position od, it has been revolved through 
45/360 of a revolution, or 45°, and an angle of 45 degrees is 
formed. 



DRAWING INSTRUMENTS 



17 



In Fig. 8, if the line oe be revolved through one-sixth of a 
revolution, it has been revolved through 60/360, or 60°, and an 
angle of 60 degrees is formed. If the line be revolved to f, one- 
twelfth of a revolution, it has been revolved 30/360, or 30°, con- 
sequently an angle of 30 degrees is formed. 




Figure 5 



Figure 7 




Figure 6 



On examination of Pig. 7, it is evident that the sum of all the 
angles about a point on the same side of a straight Une is equal 
to 180°, or two right angles. How many 60° angles about a point 
on the same side of a straight line? How many 30° angles? 



18 



MECHANICAL DRAWING 



How many 45° angles in a right angle? How many 45° angles 
about a point on the same side of straight line? What angle added 
to a 60° angle will make an 'angle of 90°? A 45° angle added to a 
30° angle makes an angle of how many degrees? 

Scales: — Draftsmen use either an architect's scale or an engi- 
neer's scale. These scales are oiten made triangular in shape. 
One edge has the inches divided into halves, quarters, eighths and 
sixteenths — other edges have scales three inches to the foot, 1^2 
inches to the foot, 2 inches to the foot, 1 Inch to the foot, and so on 
as low as 3/32 inch to the foot. On the engineer's scale the inch 
is divided into tenths, twentieths, thirtieths, fortieths, fiftieths and 
sixtieths. Scales are also made flat and in three and six inch 
lengths. 

Ihe scale is used to measure off distances on the drawing. 
The zero mark should be placed at the ponit to be measured from, 
the desired distance determined and a light line made at right 
angles with the edge. Never turn the pencil in the fingers because 
that makes an ugly hole in the paper which cannot be erased. 
When several distances are to be measured off along the same line, 
place the zero mark at the proper point measure off the first dis- 
tance, then proceed to measure off the second and third without 
moving the scale from its original position. This method secures 
greater accuracy. Never use the scale for a straight edge. Never 
mark distances on a scale with a pencil. 

Drawings are made i^", 1/2", %", 1", 11/2", 2", 3", 4", 6", 9" and 
12" to the foot. A drawing made 1" to the foot is 1/12 actual 
size; 3" to the foot, l^" actual size. 



TABLE OF SCALES 



Scale per 
foot 


Size 


Scale p 
inch 


V^" 


1/48 


1/48 


1/2" 


1/24 


1/24 


%" 


1/16 


1/16 


1" 


1/12 


1/12 


11/2" 


1/8 


1/8" 



Scale per Size 
foot 

2" 1/6 

3" 1/4 

4" 1/3 

6" 1/2 

9" 3/4 



Scale per 
inch 



1/6' 

1/4' 
1/3' 
1/2' 
3/4' 



12" to the foot is full size. 



1 1 l"''T" 


<i.>i<|i|<|ii<, 


m,i|<|i|.,.,>,i|i,l|i|.| 


|>,i,i i|.,i|m,.,>,im 


r,j,ri.|3| 


[ * ° 


:3 


6 


9 




1 i 



Figure 9 

Re erring to the 3" scale marked 3 on the architect's scale, 
Fig. 9, it is found that the 3" space has been divided into twelve 
equal parts representing inches, every third one of which has been 
marked 3, 6, 9. 



DR AWING INSTRUMENTS 19 

The divisions representing inches are subdivided to indicate 
%", 1/4" and Vs". To use the scale, from the zero point find the 
number of inches reading to the right and using the figures 3, 6, 
and 9 to aid in the reading. 5" is found, two of the inch divisions 
to the right of the division marked 3, reading from the zero; 2iA" 
is two and one-half divisions to the right of the zero point. 1 FT 
7" is found by reading to left from zero to the longer division 
marked 1 in the groove and to the right from zero to the seven 
inch division. The other scales are similarly divided and similarly 
used. 

Dividers: — This instrument consists of two pointed legs 
jointed at the top so as to be adjustable for any desired size. The 
dividers are used to transfer equal distances from one part of the 
drawing to another and to measure off several equal distances 
along a line. In doing this, care should be taken not to press too 
heavily on the points, as this makes a large hole in the paper or 
possibly bends and even breaks the steel points. This may be 
avoided by first turning the dividers for the succeeding distance 
and then pressing down just sufficiently to give a mark that may be 
seen readily. 

Compasses:— -These are very much like the dividers just de- 
scribed except that one leg has an adjustable steel point. This 
steel point has a shoulder to prevent the fine needle point from 
wearing a large hole in the paper. The other leg of the compass 
is provided with a pencil attachment as well as a pen point to 
draw circles in ink. An extension-bar is also provided for adjust- 
ment in drawing large circles. Only a slight pressure should be 
given the steel point to avoid wearing a large hole. 

Ruling Pen: — The ruling pen has two blades. The distance 
apart of the points or nibs is adjusted by means of a little set 
screw. This adjustment determines the width of the line. The 
right fine pen needs especial attention as it is used perhaps more 
than any other instrument. It must be well taken care of and 
thoroughly cleaned. Ink must not be allowed to dry on the points 
as this will corrode and ruin the pen. The adjustment, manner of 
holding and using the pen will be taken up in a chapter by itself 
later. 

Precautions to insure neatness: — In order to keep the draw- 
ing clean, it will be quite necessary to wipe the dust off the triangles 
and T-square with a clean cloth. Brush or wipe off the drawing 
each time. Brush the particles of rubber away after erasing. In 
the case of a large drawing, the finished portion may be kept 
covered. 

Arrrangement: — ^Place the drawing or drawings so that the 
sheets appear well balanced as a whole. The notes and titles 
should be placed where they may be conveniently read and so that 



20 MECHANICAL DRAWING 

they add to the appearance of the drawing. Notes whenever pos- 
sible are to be placed in a horizontal line, seldom in a vertical line. 
All figures and notes must be read from the bottom or from the 
right-hand side of the drawing. 

Rapid Drafting: — By following a few little pointers a drafts- 
man may accomplish more than he otherwise would. After the 
border line and title are laid out, block out the arrangement first. 
Get the location and general outline first, drawing in the details 
afterwards, thus building up the drawing. It is often well to put 
on the dimensions as the drawing proceeds. While the T-square 
is in hand draw all the horizontal lines possible; all vertical and 
oblique lines while the triangles are in use. Proceed in like man- 
ner with each instrument. In inking, draw all lines of the same 
width with one setting of the pen. Do all the lettering at one time. 
Repeating useless motions hinders. A definite order of doing 
things cannot be too strongly emphasized. 



INKING 

F. R. Kepler 

Having completed the pencil drawing, the student should next 
put his ruling or right line pen in working order, adjust and mark 
the little thumb screw for the different width of lines; fine, medium 
and heavy. 

Preliminary Practice: — It is well for the student using a ruling 
pen for the first time, to draw a number of lines on a loose sheet 
of paper with the triangles as guides, until he is able to draw them 
straight. At first thought this may seem easy ; however, the draw- 
ing of a straight line requires much practice. 

Manner of Holding and Using the Ruling Pen: — (1) In draw- 
ing lines with a right line pen, see that both blades bear with equal 
force upon the paper. (2) The pen should be inclined slightly in 
the direction of motion. Only pressure enough to guide it should 
be given against the straight edge, otherwise the blades will be 
forced together and a line of unequal width will result. (3) The 
lines are drawn by moving the pen from left to right, keeping it 
parallel to the first position, for if it is moved away from or toward 
the body while tracing a line, the point of the Den will become 
closer or farther away from the guiding edge and the line will be 
wavy. (4) To lessen the danger o*" blotting, the guiding edge 
should be slightly removed from the line to be drawn so that the 
pen point in tracing the line will not come in contact with it. 



INKING IN 



21 



Manner of Using the Compass: — (1) As with the ruling pen, 
the blades of the compass must bear evenly upon the paper. To 
attain this, the compass legs will have to be adjusted in the joints 
so that they will be perpendicular to the paper. (2) In describing 
arcs, allow only the weight of the compass to bear upon the needle 
point, as greater pressure will cause the point to wear a hole in the 
paper. A slight pressure may be given to the pen point, however. 
(3) The top of the compass should be but slightly inclined in the 
direction of the motion. 

Hints for Inking in a Drawing:— (1) Draw all lines of the 
same width with one setting of the pen to insure uniform width of 
line throughout the drawing. (2) When several lines radiate from 
a point, the hues should be drawn from the point, not toward it, 
allowing each hne to dry before drawing the next one in order to 
prevent a blot which is very Mkely to be made at the point. (3) 
Since it is easier to make a straight line meet a curve than other- 
wise, do the compass work first, then the straight lines. (4) In 
erasing ink lines, the best draftsmen use the steel eraser first. 
Afterward a good, clean rubber. A clean, hard, smooth substance 
is then used to make the paper smooth again and thus prevent the 
ink from spreading. Use a clean cloth or brush to remove the 
particles of rubber. (5) The student should always strive to be 
neat and should keep covered that portion of the drawing which he 
is not working upon at the time. 



ORDER OF INKING IN 



Group I. Object lines — Medium lines. 

1. Circles and arcs of circles. 

2. Irregular curves. 

3. Horizontal lines; begin at top. 

4. Vertical lines ; begin at the left. 

5. Oblique lines. 

Group II. Center, witness, and dimension lines 

Use same order as in Group I. 
Group III. Dimensions and arrow heads. Notes. Title 
Group IV. Section lines — Pine lines at 45 degrees. 
Group V. Border lines — Heavy lines. 



Pine hair lines. 



22 MECHANICAL DRAWING 



TRACING 

It is often desirable to make a more permanent and service- 
able record of a drawing than would be possible if only the inked 
original drawing were used. To accomphsh this a tracing of the 
penciled drawing is made on tracing cloth. From this tracing as 
many blue-prints as desirable may be made — these are durable, 
since they will withstand the wear and the danger of erasure from 
the weather and hard usage. 

The tracing cloth should be cut somewhat larger than the 
drawing, so that the thumb-tack holes may be removed when the 
tracing is trimmed to the proper size. This can readily be done, 
since 36" cloth actually measures 37" wide, being 36" wide between 
the red lines near the edge. 

Tack the cloth down to the board so that it will be tight and 
free from wrinkles, as the tracing may be done more rapidly. The 
cloth should have no creases or breaks in it from ill usage. Either 
the dull or the glossy side of the cloth may be used. A great many 
prefer and use the dull side because in the drafting room correc- 
tions in pencil may more readily be made on this side than on 
the glossy side. 

Dust the surface over with chalk, magnesia or talcum powder. 
Rub this hghtly into the surface and brush all the loose particles 
off thoroughly to rid the surface of grease and grit and to insure 
a ready flow of the ink. 

In order to maintain a uniform width of line throughout keep 
the same amount of ink in the pen, about a quarter of an inch at 
the most. Keep the pen clean. It will be necessary to clean the 
pen often, as little particles of chalk wiU be picked up which inter- 
fere with the even flow of the ink. If it is impossible to complete 
the whole tracing at one sitting finish one part, including circles, 
straight lines, medium and fine. This is most desirable, as the 
cloth is Hable to stretch during the intervening time between sit- 
tings,, making it difficult to readjust the tracing to the drawing. 

Erasing — Use an ordinary eraser in erasing. Never use one 
with sand in it. Never use a steel eraser. These either destroy the 
surface of the cloth, making it impossible to retrace, or a hole is 
cut in the cloth, ruining the whole tracing. After erasing it is often 
necessary to build up from a fine line to one of full weight. 



WORKING DRAWINGS 



23 



WORKING DRAWINGS 

A working drawing of a piece must have at least two views; more 
complicated pieces require three or even more views. The top view, or 
plan, shows a piece as it would be seen looking directly down on top of 
the part from above. The front view, or elevation, shows the piece as 
would be seen looking at the part from a point in front and directly on 
a level with the eye. 

If a piece of paper be folded 
so as to form the top of a box 
and the upright part the front 
of the box, we can imagine that 
the top view of an object appears 
on the level portion of the folded 
paper, while the front view ap- 
pears on the upright position of 
the paper. By unfolding the 
paper into the same level it is di- 
vided into two portions by the 
crease along which it was folded. 

This crease may represent 
a line called the Ground Line 
(G. L). This line is convenient 
in locating the drawings on the 
sheet and in explanations. 

The top view is always placed 
above the Ground Line (G. 
L). and the front view is always 
placed directly below it, in the 
same vertical line. It is evident 
that the top view of a part and 
the front view are of the same 




3"'/" 

Figure 10 



width. Suppose that the square 1, 2, 3, 4, Fig. 10, is the top view 
of a square prism with the sides 45 degrees to G. L. 

By placing the triangle against the tee-square, draw the vertical 
line 4, 4'\ the portion 4\ 4^^ of the line represents the left-hand edge of 
the prism. In Hke manner draw the line 3, 3'^ to locate the front edge, 
and 2, 2'^ to locate the right-hand edge of the prism. Draw the horizon- 
tal line 4^', 2'^ to show the base, for all the corners of the base appear in 
the same straight line when the base is on a level with the eye. Meas- 
ure off the height and draw the horizontal line 4', 2' to show the upper 



24 



MECHANICAL DRAWING 



base. It will be observed that the top view and front view of any point 
are in the same straight line perpendicular to the Ground Line 

Fig. 11 shows the drawing of a piece requiring three views. The 
making of the top and the front views is the same as that already de- 
scribed. Again, folding a piece of paper around the right-hand end of 
a box, we may imagine that we have the right-hand end view of the piece 
on this portion of the paper. Unfolding the paper out straight with the 
front of the bjx, it is observed that the end view comes at the right of 
the front view in the same horizontal line and is of the same height. 



6 














/ 


a 












/O 


7 




2 


b 


x\ 










3 


c 






O 


e 






~~~~^ 


S 










4- 


a' \ \ \ 


<? 






^^<yMc' U'l 


a' L 


■5- 


■6' 






^- 


■/' 


4' 


3' 


2" 


r 






9'- JO' 


.. 3-7' 












r 








T 


T 








a' 






























































































































s. 


-^, 


3. 


-/Q 


a- 


z 


<■ 


■/, 




' 




i 


'. 



Figure 11 
The fold, or crease, in the paper represents the front right-hand 
edge of the box. This is called the Profile Line (P. L). Having made 
the top and front views, to obtain the end view project the horizontal 
lines from 1 to a, 4 to d, on the P. L.; where the P. L. and the G. L. cross, 
or intersect, at o as a center and a radius oa draw one fourth of the arc 
of a circle until it meets G. L. at a^ In Hke manner with od as a radius 
draw the arc to d^ Draw the vertical lines a'— 1// and d'— 4// with the 
tee-square and triangle. Project the horizontal lines from V to V' and 
1/ to 1// thus getting the height of the end view. Observe that the back 
corner 1 in the top view comes at the right at V in the end view. The 
width and depth of the groove are found similarly to the outside edges. 
Also observe that the location of the hidden edges, or parts, are shown 
with short I" dashes. 



LIBRARY OF CONGRESS 



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019 934 550 3 



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